Abstract Book European Symposium on Occultation Projects 29. & 30. August 2020 www.iota-es.de @IOTAEuropeanSec Web Video Conference ESOP XXXIX © 2020, International Occultation Timing Association - European Section e.V. Am Brombeerhag 13, D-30459 Hannover, Germany Typesetting & graphic design by Oliver Klös, IOTA/ES Note: Abstracts have not been reviewed Ver. 2020-08-27 Programme Saturday, 29. August 2020 09:00 UT Welcome to ESOP XXXIX K. Guhl W. Beisker - Chairman Results & Perspectives K. Guhl - Chatcom 09:05 UT Occultations and the Size and Density of Asteroids M. Kretlow 09:30 UT Asteroidal occultations: Results from 2019 D. Herald 09:55 UT Latest developments and results at professional observatories A. Richichi Coffee Break 10:30 UT 10:45 UT Modelling and scaling neglected asteroids A. Marciniak 11:05 UT Stellar occultations and the Lucky Star project B. Sicardy 11:30 UT Occultations by Irregular Satellites of the Giant Planets A. R. Gomes-Júnior Lunch Break 12:05 UT A. Pratt - Chairman Technology N. Wünsche - Chatcom 13:00 UT Experiences from DVTI Camera Beta Tests C. Weber 13:50 UT Precise timing with digital cameras C. Valencia Gallardo Coffee Break 14:25 UT M. Kretlow - Chairman Astrometry N. Wünsche - Chatcom 14:40 UT Performance of occultation astrometry with Gaia DR2 J. F. Ferreira 15:05 UT Improvement of Asteroid Orbits for and with Asteroidal Occultations D. W. Dunham Programme Sunday, 30. August 2020 K. Guhl - Chairman Predictions & Campaigns N. Wünsche - Chatcom 09:00 UT PHEMU 2021: Mutual Phenomena of Jupiter Satellites in 2021 J. Desmars 09:15 UT Highlights of Stellar Occultations by Asteroids with Moons in 2021 in Europe and Special Events for North America & Australasia O. Klös T. Haymes - Chairman Software N. Wünsche - Chatcom 09:50 UT The Cartes du Ciel (Sky Chart) Addin for Occult Watcher W. Burzyński 10:10 UT OccultPortal: a web-based platform for data collection and analysis of stellar occultations Y. Kilic Coffee Break 10:35 UT 10:50 UT GOcEcl - a new deep asteroid occultation feed for larger apertures R. Purvinkis 11:20 UT QHY174GPS Firmware-Upgrade - Implementation and Benefits C. Weber Lunch Break 12:00 UT M. Haupt - Chairwoman Observations S. Andersson - Chatcom 13:00 UT 2 positive asteroidal occultations within 10 minutes A. Pratt 13:15 UT Propus graze occultation mystery - the history of one observation W. Burzyński 13:30 UT Descending into the Smallest Depth of an Asteroid Occultation P. D. Maley Coffee Break 14:00 UT 14:15 UT The partial and nearly grazing solar eclipse of June 21, 2020 and solar diameter measurements C. Sigismondi K. Guhl - Chairman Next ESOPs & Closing N. Wünsche - Chatcom 14:45 UT Announcing ESOP 2021 in Bialystok (Poland) W. Burzyński 14:55 UT Announcing ESOP 2022 in Granada (Andalucía/Spain) P. Santos-Sanz & C. Schnabel 15:05 UT Closing Remarks K. Guhl Results & Perspectives Occultations and the Size and Density of Asteroids M. Kretlow 1∗ 1International Occultation Timing Association, European Section (IOTA/ES); D-27389 Lauenbrück, Germany 1 Introduction Asteroids are described by dynamical parameters (orbit, dynam- ical class, families, etc.), by their physical properties, and fi- nally also by their chemical composition. Size, mass, density, and macro porosity are prime physical properties and important for our understanding of the internal structure and morphology of asteroids (Scheeres et al., 2015). With an increasing amount of size, mass and thus density data, new statistical approaches are possible revealing further struc- tures in the asteroid belt and population, with implication on the description of the current and former state of the Solar System. However, we yet have density estimates for only some hundred objects, and only about 1/3 of them have a relative accuracy better than 20%. With very few exceptions, bulk densities are calculated from individual size and mass estimates. We need more data and many of the existing ones should be Figure 1: Annual number of successful observed stellar occul- confirmed and improved in accuracy, where possible. This is a tations by asteroids in Europe. The release dates of astrometric huge and continuous task, covering different (observational and star catalogs with high impact on occultation predictions are theoretical) domains – and another example of fruitful pro-am indicated. collaborations, as many rotational light curve photometry (see CALL website) and occultation oberservations are provided by amateurs. tion) existing diameter estimates derived by other methods (e.g. radiometric), and they are very helpful to scale 3D models de- rived from rotational light curve inversion and thus to provide 2 Size and Mass estimates accurate volumes of irregular bodies. When the book Asteroids III was released in 2002, the chapter on masses and densities by Hilton listed only ∼50 individual 3 Web Archive and Portal mass estimates for ∼25 different asteroids. The list on individ- ∼ ual bulk densities ρ was even smaller. The limiting factor at that Carry (2012) compiled from the literature 1000 mass and ∼ time was the availability of asteroid mass estimates, which are 1500 size estimates and derived from that mean bulk densities systematically much harder to derive than size measurements. and macro porosities for about 300 asteroids. These data were Size estimates were already available for almost 2000 asteroids only available in that publication, not in a machine-readable due to IRAS obervations and from stellar occultations. But with form. This work is a continuation of that effort. It is an up- increasing accuracy of mass estimates, the uncertainty of the to-date and (mostly) complete collection of size and mass esti- diameter D can now be the limiting factor for the resulting un- mates, providing researchers with ready to use data. Moreover this web portal also provides some visualization and interac- certainty in density, because ∆ρ/ρ = (∆M/M)2 + 9(∆D/D)2. √ tive handling of the data, helping researchers to address certain questions and data science tasks. 2.1 Stellar occultations The number of predicted and successful observed occultations References by asteroids has increased significantly in the past two decades due to increasing and better resources and collaboration tools, Carry, B. Density of asteroids. Planetary and Space Science, and a growing community of observers (Figure 1). The Gaia 73(1):98–118, 2012. star catalog release boosted that once more. Meanwhile occul- Ferreira, J.F., Tanga, P., Machado, P. et al. A survey for occul- tations are not only used to derive size and shape of asteroids, tation astrometry of main belt: expected astrometric perfor- but also to get a considerable amount of Gaia level (mas to sub- mances. arXiv preprint arXiv:2007.09665, 2020. mas) astrometric positions, even with single chord observations (Ferreira et al., 2020). Hilton, J.L. Asteroid masses and densities. Asteroids III, 1: 103–112, 2002. Stellar occultations play an important role in establishing and extending the list of known densities of asteroids as the number Scheeres, D., Britt, D., Carry, B. et al. Asteroid interiors and of mass estimates is growing as well. They confirm (or ques- morphology. Asteroids IV, 745766, 2015. *Correspondence: [email protected] Results & Perspectives Asteroidal occultations: Results from 2019 Dave Herald, IOTA I will provide update the statistics about occultation observations from around the world from those I presented at ESOP 38. And I will show the best 11 occultation results of the year. Results & Perspectives Latest developments and results at professional observatories Andrea Richichi (INAF - Arcetri, Italy) and co-authors Programs for observing occultations are currently in place at a few professional observatories around the world. I will give a brief overview of such efforts at facilities in Germany, India, Italy, Russia. In particular, I will report on exciting new developments and results in the area of spectroscopically dispersed lunar occultations and a recent asteroidal occultation of a binary star leading to the smallest angular diameter ever measured directly. Results & Perspectives Modelling and scaling neglected asteroids Anna Marciniak, IOTA/ES, University of Poznan In the Astronomical Observatory Institute of Poznan, Poland we are coordinating a worldwide observing campaign of somewhat neglected asteroids. These are small bodies of the main belt with slow rotation and small lightcurve amplitudes. The aim is to improve biased statistics of spin and shape modelled asteroids. We focus mainly on multi-apparition photometric observations, lightcurve inversion modelling, and scaling those models with thermal infrared data. However, many of these asteroids have poor thermal datasets and cannot be precisely scaled this way. This is where good occultation campaigns can greatly help. Results & Perspectives Stellar occultations and the Lucky Star project Bruno Sicardy, LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, 92195 Meudon, France ([email protected]) The European Research Council (ERC) project “Lucky Star" aims at exploring the outer Solar System using stellar occultations and theoretical tools to interpret those observations. It is currently the world-wide leader in its domain. As of April 2020, more than 185 events have been successfully recorded, with more than 70 objects detected, among which about 30 Trans-Neptunian objects, 5 dwarf planets, 6 Centaur objects and more than 20 Trojan asteroids. Here I review a few highlights of the past year, concerning Triton’s atmosphere, the shape of V a r d a and the recent densely observed occultation by 2002 MS4 . Results & Perspectives Occultations by Irregular Satellites of the Giant Planets Altair R. Gomes-Júnior (1,2) (1) UNESP - São Paulo State University, Grupo de Dinamica Orbital e Planetologia, Guaratinguetá, SP, Brazil ([email protected], [email protected]) , (2) Laboratório Interinstitucional de e-Astronomia - LIneA, Rio de Janeiro-RJ, Brazil The irregular satellites are objects that orbit the Giant Planets from great distances, with highly inclined, eccentric orbits and mostly retrograde.